refactor(state): drop unused args + lift currentPhase in cmdStateCompletePhase (#2761)

* refactor(state): drop unused args param and lift currentPhase in cmdStateCompletePhase

Two cleanup items surfaced by CodeRabbit review of PR #2759:

1. cmdStateCompletePhase(cwd, args, raw) — args is never read inside the
   function. All sibling state subcommands use the leaner (cwd, raw) shape.
   Remove the unused parameter and update the dispatch call in gsd-tools.cjs.

2. output() at line 1754 called fs.readFileSync(statePath) after
   readModifyWriteStateMd had already released the lock, re-extracting
   Current Phase via an extra fs read. The closure already computed
   currentPhase at line 1704; lifting resolvedPhase into outer scope and
   capturing it in the callback eliminates the post-lock read and closes the
   small race window.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

* test(#2761): apply CodeRabbit nitpicks with regression tests

Two CodeRabbit nitpicks from PR #2761 review, each landed with a
regression test so a future refactor can't unwind them.

1. tests/dispatcher.test.cjs — pin the enumerated subcommand list:
   the 'state unknown subcommand errors' test now also asserts that
   the dispatcher's error string includes 'complete-phase'. Without
   this, a future reformat of the available-subcommands enumeration
   could silently drop entries and the existing
   'Unknown state subcommand' substring check would still pass.

2. get-shit-done/bin/lib/state.cjs — tighten the Phase fallback in
   cmdStateCompletePhase: when STATE.md is missing the canonical
   '**Current Phase:**' field and the only phase signal is the
   decorated body line under '## Current Position' (e.g.
   'Phase: 01 (Foo) — EXECUTING'), the previous fallback returned
   the entire decorated string, producing messy downstream output:
     Status: Phase 01 (Foo) — EXECUTING complete
     Phase: 01 (Foo) — EXECUTING — COMPLETE
   The fallback now strips everything past the leading
   numeric/decimal token via /^\\s*([\\w.-]+)/ so degraded inputs
   produce clean output identical to the canonical path.

3. tests/state.test.cjs — two new tests in a dedicated describe block:
   - decorated Phase line writes clean Phase identifier
   - canonical Current Phase wins over Current Position decoration
   Both run real `gsd state complete-phase` against synthetic
   STATE.md fixtures and assert on the rendered Status field.

---------

Co-authored-by: Claude Sonnet 4.6 <noreply@anthropic.com>

get-shit-done/bin/gsd-tools.cjs

@@ -484,7 +484,7 @@ async function runCommand(command, args, cwd, raw, defaultValue) {
         const { 'keep-recent': keepRecent, 'dry-run': dryRun } = parseNamedArgs(args, ['keep-recent'], ['dry-run']);
         state.cmdStatePrune(cwd, { keepRecent: keepRecent || '3', dryRun: !!dryRun }, raw);
       } else if (subcommand === 'complete-phase') {
-        state.cmdStateCompletePhase(cwd, args, raw);
+        state.cmdStateCompletePhase(cwd, raw);
       } else if (subcommand === 'milestone-switch') {
         // Bug #2630: reset STATE.md frontmatter + Current Position for new milestone.
         // NB: the flag is `--milestone`, not `--version` — gsd-tools reserves