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>

governance/decisions/process.md

@@ -59,7 +59,7 @@ How the team works: composition, naming, workflow.
 - **Design principles:** (1) Game-first, not encyclopedia-first — every entry serves the content pipeline. (2) Hierarchical with cross-references via IDs, not file paths. (3) Metadata-rich YAML frontmatter enabling programmatic queries. (4) Template-driven — new entries follow category templates. (5) Every entry has a `status` field: `proposed` → `draft` → `canonical`.
 - **Governance:** Miri owns wiki structure (new categories, templates, structural decisions). Anyone can create entries within their domain following templates. Qatux maintains the index and cross-references.
 - **Cross-reference:** Setting ([D-036](content.md#d-036-sova-transit-district--van-maanens-star-system-as-v01-setting))
-- **Raised by:** Miri (Round 2 proposal with full directory structure and 7 YAML schemas), project lead (non-negotiable, directive #5)
+- **Raised by:** Miri (Round 2 proposal with full directory structure and 7 YAML schemas), project lead (non-negotiable, directive T-5)
 - **Dissent:** None
 
 ---