fix(workflows): skip runs that cannot change a result

[davidmoralesz]

What changed, and why

Two changes inside the reusable workflows, so every consumer at @v1 inherits them with no PR of their own:

• ci-pr: skip the job for Dependabot PRs (never linted anyway), and for edited events that change neither the title nor the base branch. release-please and Dependabot rewrite their PR bodies on every push, and the body is never read. In bimo-mod, 88 pr-checks runs this month were mostly these.
• All ci-* workflows: job-level concurrency that cancels a pull request run when a newer push supersedes it. Pushes to the default branch, merge groups and schedules never cancel. The group is <lib>-<caller workflow>-<ref>, so it stays per repo and never collides with a caller's own workflow-level group.

Both are inside the callee on purpose: a skipped callee job still reports its full check name, so required checks stay satisfied, which a skipped caller job would not guarantee. No paths: filters, for the same reason.

Stacked on #60 (base branch chore/monthly-dependabot).

How it was tested

• actionlint, zizmor .github/workflows, prettier and sh .devtools/check-action-pins.sh are clean.
• Cross-repo: studiobimo/bimo-mod#64 is a draft that pins its wrappers to this branch's SHA; its test plan covers cancel-on-push, body edit (skipped, check still reported), title edit (re-runs) and a Dependabot PR. I'll link the runs here.

Checklist

• Title is a Conventional Commit; branch follows Conventional Branch
• At most 20 files changed (7)
• No new third-party uses:
• permissions unchanged
• Not breaking, but behaviour changes for every consumer: PR runs now cancel on a newer push