fix: extend fix-slash-commands SEARCH_DIRS to agents/, sdk/src/, .clinerules

scripts/fix-slash-commands.cjs SEARCH_DIRS did not cover agents/, sdk/src/,
or top-level files, so 9 colon-form references survived in 6 files. The hit
at agents/gsd-codebase-mapper.md:105 propagated into ~/.claude/agents/ at
install time (the fixer is not wired into install) and produced unrunnable
/gsd:<cmd> suggestions in agent output on non-Gemini runtimes.

This commit includes Pass 1 (the 9 line edits) AND Pass 2 (extending the
fixer's SEARCH_DIRS so future regressions are auto-rewritten and caught by
the bug-2543 guard, which mirrors that list). The standalone bug-3100 test
added in the prior revision is removed in favor of the bug-2543 guard's
extended scan, per CONTRIBUTING.md test standards (no source-grep tests on
non-.md files).

Refs #3100

sdk/src/query/state-mutation.ts

@@ -1128,7 +1128,7 @@ export const statePlannedPhase: QueryHandler = async (args, projectDir, workstre
  * Query handler for `state.milestone-switch` — resets STATE.md for a new
  * milestone cycle (bug #2630 regression guard).
  *
- * The `/gsd:new-milestone` workflow only rewrote STATE.md's body (Current
+ * The `/gsd-new-milestone` workflow only rewrote STATE.md's body (Current
  * Position section). The YAML frontmatter (`milestone`, `milestone_name`,
  * `status`, `progress.*`) was never touched on a mid-flight switch, so queries
  * that read frontmatter (`state.json`, `getMilestoneInfo`, every handler that
@@ -1151,7 +1151,7 @@ export const statePlannedPhase: QueryHandler = async (args, projectDir, workstre
  *
  * Sibling CJS parity: `cmdInitNewMilestone` in `init.cjs` is read-only (like
  * the TS `initNewMilestone`). The workflow-level fix is to call
- * `state.milestone-switch` from `/gsd:new-milestone` Step 5 in place of the
+ * `state.milestone-switch` from `/gsd-new-milestone` Step 5 in place of the
  * manual body rewrite.
  */
 export const stateMilestoneSwitch: QueryHandler = async (args, projectDir, workstream) => {

sdk/src/query/verify.ts

@@ -649,7 +649,7 @@ export const verifySchemaDrift: QueryHandler = async (args, projectDir, workstre
  *
  * Non-blocking by contract: every failure mode returns a successful response
  * with `{ skipped: true, reason }`. The post-execute drift gate in
- * `/gsd:execute-phase` relies on this guarantee.
+ * `/gsd-execute-phase` relies on this guarantee.
  *
  * Delegates to the Node-side implementation in `bin/lib/drift.cjs` and
  * `bin/lib/verify.cjs` via a child process so the drift logic stays in one