Repo polish: MIT license, CI, and a README that shows the product

.github/FUNDING.yml

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+# Shows a "Sponsor" button on the repo. Fill in the handles you actually use;
+# delete the lines you don't. GitHub validates these, so a wrong handle just
+# hides that entry rather than breaking the page.
+github: [Alvaro5]          # requires GitHub Sponsors enabled on your account
+# ko_fi:            your-handle
+# buy_me_a_coffee:  your-handle
+# custom: ["https://gradepace.vercel.app"]

.github/ISSUE_TEMPLATE/bug_report.yml

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+name: Bug report
+description: Something in the pacing plan or UI is wrong or broken.
+labels: [bug]
+body:
+  - type: markdown
+    attributes:
+      value: |
+        Thanks for the report. GradePace runs entirely in your browser, so the
+        more you can tell me about the GPX and your setup, the faster this gets fixed.
+  - type: textarea
+    id: what-happened
+    attributes:
+      label: What happened?
+      description: What did you see, and what did you expect instead?
+      placeholder: "The projected finish was 3:12 but the course is 70 km, so that can't be right..."
+    validations:
+      required: true
+  - type: textarea
+    id: gpx
+    attributes:
+      label: The GPX file
+      description: >
+        If you can share the course (a link, or drag the file into the comment
+        box after creating the issue), that makes it reproducible. Note if it's a
+        recorded track (with times) or a route export.
+    validations:
+      required: false
+  - type: input
+    id: settings
+    attributes:
+      label: Settings
+      description: Flat pace, VAM, hike gate, terrain factor, units, language, if relevant.
+      placeholder: "6:00/km, VAM 750, gate 18%, terrain x1.04, metric, EN"
+    validations:
+      required: false
+  - type: input
+    id: env
+    attributes:
+      label: Browser / device
+      placeholder: "Chrome 141 on macOS, or Safari on iPhone"
+    validations:
+      required: false

.github/ISSUE_TEMPLATE/config.yml

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+blank_issues_enabled: true
+contact_links:
+  - name: Try GradePace
+    url: https://gradepace.vercel.app
+    about: The live app. Load an example course to see the full output before filing.

.github/ISSUE_TEMPLATE/feature_request.yml

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+name: Feature request
+description: Suggest something that would make the pacing plan more honest or the app more useful.
+labels: [enhancement]
+body:
+  - type: textarea
+    id: problem
+    attributes:
+      label: What are you trying to do?
+      description: Describe the racing/planning problem, not just the feature. What can't you do today?
+    validations:
+      required: true
+  - type: textarea
+    id: idea
+    attributes:
+      label: Your idea
+      description: How would you like it to work? Rough is fine.
+    validations:
+      required: false
+  - type: checkboxes
+    id: thesis
+    attributes:
+      label: Fit check
+      description: GradePace is deliberately about honest self-calibration, not false precision. (Optional.)
+      options:
+        - label: This is about a more honest or personal prediction, not just more knobs to tune.

.github/pull_request_template.md

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+<!-- Keep PRs small and focused: one idea each. -->
+
+## What and why
+
+<!-- What does this change, and what problem does it solve? -->
+
+## Checklist
+
+- [ ] `npm run lint && npm test && npm run build` all pass
+- [ ] Added or updated tests for any engine/behavior change
+- [ ] If this moves the projected finish time, I've called that out explicitly
+- [ ] STATUS.md / README updated if the change affects them

.github/workflows/ci.yml

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+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    branches: [main]
+
+# Cancel superseded runs on the same ref (e.g. rapid pushes to a PR).
+concurrency:
+  group: ci-${{ github.ref }}
+  cancel-in-progress: true
+
+jobs:
+  build-and-test:
+    name: Lint, test, build
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+
+      - name: Set up Node
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22
+          cache: npm
+
+      # `npm install`, not `npm ci`: sharp and the tailwind-oxide / rolldown
+      # wasm fallbacks pull nested, platform-specific optional deps that a
+      # macOS-generated lockfile can't fully describe for a Linux runner, so
+      # `npm ci`'s strict lockfile check fails. `npm install` reconciles the
+      # tree for whatever platform the runner is.
+      - name: Install dependencies
+        run: npm install --no-audit --no-fund
+
+      - name: Lint
+        run: npm run lint
+
+      - name: Test (Vitest)
+        run: npm test
+
+      - name: Build
+        run: npm run build

CONTRIBUTING.md

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+# Contributing to GradePace
+
+Thanks for taking a look. GradePace is a small, opinionated project with a real
+race behind it, so contributions are welcome but the bar is "does this make the
+pacing plan more honest or the app more useful," not "more features."
+
+## Ground rules
+
+- **The engine is the asset.** `src/lib/pacing.ts` is pure TypeScript: no React,
+  no DOM, fully unit-tested. Domain logic lives there and stays testable. UI
+  glue lives in `src/App.tsx` and the component files.
+- **Verify against reality, not vibes.** Distances should match known race
+  lengths, D+ should match published figures, and the Minetti cost model must
+  match the 2002 paper's measured anchors. There are tests that lock these.
+- **Keep the tests green.** `npm test` must pass. A coefficient typo should fail
+  loudly, so please add a test when you add behavior.
+- **Honest uncertainty over false precision.** The product presents a finish
+  *range* on purpose. Changes that pretend to more accuracy than a GPX-only
+  prediction can deliver will be pushed back on.
+
+## Getting set up
+
+```sh
+npm install
+npm run dev      # local dev server
+npm run test     # engine + app tests (Vitest)
+npm run lint
+npm run build    # production build (also what CI runs)
+```
+
+## Proposing a change
+
+1. Open an issue first for anything non-trivial, so we can agree on the shape
+   before you write code. Bug reports with the GPX file (or a link) and what you
+   expected vs. saw are the most useful.
+2. Keep pull requests small and focused. One idea per PR.
+3. Don't bundle a model/behavior change (anything that moves the projected
+   finish time) into an unrelated PR. Call it out so it can be reviewed on its
+   own merits.
+4. Run `npm run lint && npm test && npm run build` before pushing.
+
+## Where things are
+
+The current technical state, decisions, and roadmap live in
+[STATUS.md](./STATUS.md). Read it first. The high-level architecture is in the
+[README](./README.md#project-structure).

LICENSE

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+MIT License
+
+Copyright (c) 2026 Alvaro Serero
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.