0.17 phase 5 PR A: static alias file parser (#141)

* feat(gc-suggest): static alias-file parser; prefer over zsh subprocess

Reads ~/.zshrc, .zshenv, .zsh_aliases, oh-my-zsh/custom/*.zsh, etc.
Falls back to 'zsh -c alias' only when the static path is empty.
Conservative: skips multi-line aliases and 'alias -g/s/L' forms.

* chore(gc-suggest): align alias cache fingerprint with files actually parsed

* style(gc-suggest): satisfy clippy::unnecessary_get_then_check in alias tests

* fix(gc-suggest): harden static alias parser (quotes, names, file order)

Address review findings on the new static alias parser:

- Parse '#' inside quoted alias values via a quote-aware value scanner.
  Trailing inline comments are still stripped, but '#' in URLs, fragments,
  and hex colors inside quotes is now preserved instead of truncating the
  value to a corrupt fragment.
- Accept dotted and hyphenated alias names (.., ..., git-st) while still
  rejecting `alias -g/-s/-L` global/suffix forms and punctuated names.
- Drop every physical line of a backslash-continued statement so a
  continuation tail can no longer register a phantom alias.
- Reorder STATIC_ALIAS_FILES / ALIAS_SOURCE_FILES to true last-read-wins
  precedence and restore .zprofile; make the file-order doc comment match
  the array and document the subprocess-fallback trade-off.
- Add tracing::debug! breadcrumbs when an alias line is rejected or dropped.
- Add tests: oh-my-zsh custom drop-in walk, cross-file override order,
  '#'-in-value, name acceptance/rejection, shlex whitespace fallback, and
  the empty-home subprocess-fallback precondition.

* test(gc-suggest): lock alias read-set==watch-set invariant; polish drop paths

Address iteration-2 review findings on the static alias parser:

- Add a test asserting STATIC_ALIAS_FILES and ALIAS_SOURCE_FILES are
  set-equal in both directions and that the parser-walked
  .oh-my-zsh/custom dir is a member of ALIAS_SOURCE_DIRS, so the
  read-set/watch-set mirror invariant can no longer drift silently and
  reintroduce the stale-cache bug this PR exists to prevent.
- Sort oh-my-zsh custom *.zsh drop-ins before ingest for deterministic
  override order across machines.
- Log non-NotFound dotfile read errors (permission/encoding) at debug
  instead of swallowing them silently.
- Add a debug breadcrumb when skipping a backslash-continued statement.
- Drop the inaccurate "unescaped" wording from the continuation comment.

Author: StanMarek