Emit accepted line fingerprint analytics (#21601)

## Why

Codex assisted-code attribution needs a client-side accepted-code source
that does not upload raw code. This adds a hash-only analytics event
derived from the turn diff so downstream attribution can compare
accepted Codex lines against commit or PR diffs.

## What Changed

- Parse accepted/effective added lines from the final turn diff and emit
`codex_accepted_line_fingerprints` analytics.
- Hash repo, path, and normalized line content before upload; raw code
and raw diffs are not included in the event.
- Chunk large fingerprint payloads and send accepted-line fingerprint
events in isolated requests while preserving normal batching for other
analytics events.
- Canonicalize Git remote URLs before repo hashing so SSH/HTTPS GitHub
remotes join to the same repo hash.
- Add parser coverage for unified diff hunk lines that look like `+++`
or `---` file headers.

## Verification

- `cargo test -p codex-analytics`
- `cargo test -p codex-git-utils canonicalize_git_remote_url`
- `just fix -p codex-analytics`
- `just bazel-lock-check`
- `git diff --check`

codex-rs/git-utils/src/lib.rs

@@ -24,6 +24,7 @@ pub use errors::GitToolingError;
 pub use info::CommitLogEntry;
 pub use info::GitDiffToRemote;
 pub use info::GitInfo;
+pub use info::canonicalize_git_remote_url;
 pub use info::collect_git_info;
 pub use info::current_branch_name;
 pub use info::default_branch_name;