Fix README links, add missing skills, correct invocation classification

- Fixed 3 broken links in root and common READMEs (pkm-curation,
  forge-interaction, forge-preferences were pointing to wrong buckets)
- Moved project-context-pack from model-invoked to user-invoked
  (matches its disable-model-invocation: true flag)
- Added 8 missing user-invoked and 6 missing model-invoked skills
  to root and common READMEs
- Added all 9 engineering skills to engineering README
  (was missing codebase-design, domain-modeling, resolving-merge-conflicts,
  tdd, grill-with-docs, improve-codebase-architecture, setup-skills,
  to-issues, to-prd, triage)
- Added pkm-curation to pkm README
- Updated personal README to note both skills moved elsewhere
- Added all forge skills to deprecated README
- Added .gitignore for docs/adr/
- Added docs/agents/ reference files
- Added project context cache

docs/agents/triage-labels.md

@@ -0,0 +1,13 @@
+# Triage Labels
+
+The skills speak in terms of five canonical triage roles. This file maps those roles to the actual label strings used in this repo's issue tracker.
+
+| Label in skills | Label in our tracker | Meaning                                  |
+| -------------------------- | -------------------- | ---------------------------------------- |
+| `needs-triage`             | `needs-triage`       | Maintainer needs to evaluate this issue  |
+| `needs-info`               | `needs-info`         | Waiting on reporter for more information |
+| `ready-for-agent`          | `ready-for-agent`    | Fully specified, ready for an AFK agent  |
+| `ready-for-human`          | `ready-for-human`    | Requires human implementation            |
+| `wontfix`                  | `wontfix`            | Will not be actioned                     |
+
+When a skill mentions a role (e.g. "apply the AFK-ready triage label"), use the corresponding label string from this table.