Fix Claude Code project names collapsing to a parent folder

[ozymandiashh]

Summary

Closes #493 by showing the real Claude Code project leaf in the "By Project" panel (TUI + menubar dropdown) and stopping sibling projects from collapsing under a parent folder.

Root cause

Two independent paths produced a parent folder or a wrong fragment instead of the project leaf:

1. Stray ancestor .git over-grouping. resolveCanonicalProjectPath (src/parser.ts) walked up to the nearest .git and used it as the canonical project path. That is correct for a real linked worktree, but if a parent directory of several projects happens to contain a .git (a dotfiles bare repo, an accidental git init in ~/Projects/), every sibling resolved to that parent — so the panel rendered Projects (or home) for all of them.
2. Hyphenated names destroyed in the no-cwd fallback. When a Claude session has no cwd metadata, projectPath fell back to unsanitizePath(dirName), which blindly replaces every - with /. A slug like Projects-Content-OS became projects/content/os, and projectName() then pop()-ed it to os.

What changed

• resolveCanonicalProjectPath now canonicalizes to the main repo only for a real linked git worktree (.git is a file whose gitdir: points at <main>/.git/worktrees/<name>). For an ordinary repo, or when a .git is found only at an ancestor, it keeps the session's own cwd instead of absorbing it into the parent.
• The Claude no-cwd fallback keeps the lossy directory slug intact (claudeSlugFallbackPath) instead of inventing path segments.
• projectName() (src/overview.ts) only basenames absolute paths; a relative slug-shaped name is shown as-is rather than split on invented separators.
• Regression tests in tests/parser-claude-cwd.test.ts and tests/overview.test.ts for: sibling projects under a shared parent .git, hyphenated slug with absent cwd, and the no-cwd fallback. One existing test that asserted the old fallback-slug -> fallback/slug behavior was updated to expect the slug kept intact.

Behavior change worth flagging (re: #375)

PR #375 ("Group git worktrees under main project") also caused sessions launched from a subdirectory of an ordinary repo to group up to the repo root. With this change, a non-worktree subdirectory session keeps its own cwd (it appears under its own directory rather than the repo root). Real git-worktree grouping is unchanged. I went with the worktree-only rule because there is no unambiguous signal to tell a project's own repo from an accidental ancestor .git. If you'd prefer to preserve subdirectory-to-repo-root grouping for ordinary repos, I'm happy to take a more surgical approach — just let me know.

Validation

Checks run (en_US locale):

npm test -- --run tests/parser-claude-cwd.test.ts tests/overview.test.ts tests/providers/claude.test.ts  - 20 tests passed
npm test -- --run                                                                                         - 1275 tests passed
npx semgrep --config .semgrep/rules/no-bracket-assign-hot-paths.yml src/                                  - 0 findings
npm run build (bundle-litellm + tsup)                                                                     - build success
npx tsc --noEmit                                                                                          - clean

The new tests fail on origin/main (verified by reverting only the source change) and pass with the fix, so the fix is causally required. Worktree-grouping and separate-git-dir tests remain green.

Notes

• npm run build regenerated src/data/litellm-snapshot.json / pricing-fallback.json; both were restored — unrelated to this fix.