Make the compiled snapshot see uncommitted CLI sources

[MAUstaoglu]

The problem

tool_revision in bin/internal/shared.sh decides whether bin/cache/flutter-tvos.snapshot is stale. Its git branch returned git rev-parse HEAD — which describes what was committed, not what is on disk.

In a development checkout those differ constantly. Edit anything under lib/, run the CLI, and it silently executes the previously compiled snapshot.

The failure mode is why this is worth fixing rather than documenting. The change does not appear to be ignored — it appears to be wrong. You get the same build, the same error, byte for byte, and conclude the fix is incorrect when in fact it never ran. rm bin/cache/flutter-tvos.snapshot is the folk remedy, for anyone who has been told it.

It cost me a full build cycle and a byte-identical error I nearly misread as "my patch doesn't work".

The fix

The non-git branch of this same function never had the problem — it hashes the contents of bin/ and lib/, so it is content-addressed by construction. This makes the git branch agree, by folding uncommitted work into the revision.

• Scoped to bin, lib, pubspec.yaml, pubspec.lock, so editing a README or a test does not force a recompile.
• Hashes status --porcelain and diff HEAD. Names and statuses alone would collide across two different edits to the same file; the diff alone would miss a newly added one.
• Only paid when the tree is dirty. A clean checkout returns the bare 40-character sha exactly as before, so nobody who is not editing the CLI sees any change at all.

Tests

Nine cases in test/general/tvos_snapshot_revision_test.dart, driving the real bash function in a throwaway git repository: clean checkout returns bare HEAD; edits under lib/ and bin/ move it; a new untracked source moves it; two different edits to one file do not collide; the value is deterministic rather than a nonce; reverting restores it; README/test edits do not move it; committing returns to a bare sha.

Six of the nine fail against the unfixed shared.sh. The three that pass either way are the ones asserting unchanged behaviour, which is what they are for.

Baseline

The suite is not currently green on main: 58 failures there, and the same 58 here. Passes go 373 → 382, exactly the nine added.

Note on versioning

No version bump here deliberately — #74 is open and bumps to 1.10.0, and a second bump would just conflict. This should ride whichever release lands next.

[MAUstaoglu]

Folded into #74 so 1.10.0 lands as one release — the two fixes are the same piece of work, and the snapshot bug is what made the first one look broken while I was writing it. Same commits, same tests.