docs(meta): switch ticket-reference convention #N -> T-N (pql migration phase 3)

Adopts the T-NNN convention (T-N == old #N == pql ticket id) across the active
operational layer: governance/ decision records, .claude/{rules,agents,skills},
CLAUDE.md, DECISIONS.md. 283 references rewritten.

Guarded against false positives (17 correctly skipped, each logged):
  - PR references kept (PR #136/#138/... — PRs are a separate #-namespace)
  - non-ticket numbers kept (#4122; the "#1 process failure" idiom; "task #3")
  - only #N where N is an actual ticket id is rewritten; the 1-4 digit word-bounded
    match also excludes 6-digit hex colours in the visual decision records

Git history is NOT rewritten (a commit's #N already equals T-N numerically), and
historical archives (docs/sprints, docs/discussions, docs/workshops) keep their
point-in-time #N. The /pr-process ticket-ID extraction logic moves to T-NNN in the
Phase 4 consumer cutover.

Verified: pql decisions validate ok; sync 357 records / 1057 refs / broken 0 (the
prose edits don't affect decision parsing or the tickets.decision_ref linkage).
Transform committed at tooling/pql-migrate/retag_ticket_refs.py.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

.claude/agents/clerk.md

@@ -9,7 +9,7 @@ You are the CLERK, the institutional guardrail on a game development team buildi
 
 ## Your personality
 
-Precise, dispassionate, thorough. You are not a reviewer — you don't judge code quality. You are a consistency checker. You say things like "File X contradicts D-142" and "Ticket #890 describes outcome Y but implementation does Z." You do not have opinions about design. You have facts about what was decided and whether the code matches.
+Precise, dispassionate, thorough. You are not a reviewer — you don't judge code quality. You are a consistency checker. You say things like "File X contradicts D-142" and "Ticket T-890 describes outcome Y but implementation does Z." You do not have opinions about design. You have facts about what was decided and whether the code matches.
 
 ## Your role