feat: preserve presentation slide identity

[buildwithrohith]

Summary

• Emit Inline::Anchor("slide-N") for every PPTX, legacy PPT, and ODP slide in source order, including empty slides.
• Emit Block::Rule only between content-bearing slides. Empty slides retain their anchor and do not add a doubled separator.
• Add four-slide fixtures covering titled, untitled, and empty slides for all three presentation parsers, plus the PPTX internal-link regression.
• Retarget the CI and release workflows from Blacksmith labels to GitHub-hosted runners.
• Replace npm publication with CI packing. The release workflow stages all seven native .node artifacts, runs npm pack --ignore-scripts, verifies native files in the tarball, and uploads the tarball to the GitHub release.

Distribution decision

Chosen option (b), vendor a packed tarball. The available npm credential is the personal vishhvak account and has no Sapiex organization scope, so publishing a production dependency under that account is not acceptable. No npm publish command was run, and the release workflow contains no npm publish command. The Node package now includes anydoc.*.node in its files list so one packed archive is self-contained on every target. The release workflow also packs the existing Wasm package as a release asset instead of publishing it.

The local Darwin smoke archive was:

/tmp/anydoc-pack-final.oJfJrY/firecrawl-anydoc-0.1.7.tgz

Its literal contents included:

package/README.md
package/anydoc.darwin-arm64.node
package/cli.js
package/index.d.ts
package/index.js
package/package.json
{"anchors":["slide-1","slide-2","slide-3","slide-4"],"rules":2}

The seven-target CI matrix remains the source for the release asset used by Sapiex.

Verification

Actual command output:

$ cargo test --locked --quiet
running 208 tests
....................................................................................... 87/208
....................................................................................... 174/208
..................................
test result: ok. 208 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.02s

running 1 test
.
test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 1.12s

running 11 tests
i..........
test result: ok. 10 passed; 0 failed; 1 ignored; 0 measured; 0 filtered out; finished in 0.14s

running 0 tests
test result: ok. 0 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out; finished in 0.00s

$ cargo clippy --workspace --all-targets --all-features -- -D warnings
    Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.09s

$ cargo fmt --all --check

$ ruby -e 'require "yaml"; ARGV.each { |path| YAML.load_file(path); puts "#{path}: parsed" }' .github/workflows/ci.yml .github/workflows/release.yml
.github/workflows/ci.yml: parsed
.github/workflows/release.yml: parsed

Node pack and binding smoke output:

$ npm test
ℹ tests 13
ℹ suites 0
ℹ pass 13
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0

$ npm pack --ignore-scripts --pack-destination /tmp/anydoc-pack-final.oJfJrY
npm notice 6.9MB anydoc.darwin-arm64.node
npm notice total files: 6
npm notice filename: firecrawl-anydoc-0.1.7.tgz

$ installed packed archive and called toDocument on handmade-slide-identity.pptx
{"anchors":["slide-1","slide-2","slide-3","slide-4"],"rules":2}

Upstream split

The model and tests are isolated in commit d7f5a2d and pushed as upstream-slide-identity. The fork-only CI and release changes are in 40528db.