feat(hands): add wiki hand for LLM-maintained knowledge bases (#44)

Squashed replay of the original 9-commit branch onto current main.  The
original branch was 30+ commits behind, forked from before the skills
refactor (PR #42) and workflow template expansion (PR #36), so a
standard rebase hit heavy add/add conflicts on workflows/*.toml that
are unrelated to the wiki hand.

This replay keeps only the final hands/wiki/ tree state, which is the
actual intent of the PR (the author iterated several times on the same
files; squashing matches that).

Implements the "LLM Wiki" pattern (Andrej Karpathy) for building a
personal, Obsidian-compatible knowledge base.  Instead of on-the-fly
RAG, the wiki hand incrementally maintains a Markdown vault:

  hands/wiki/
  ├── HAND.toml           # hand manifest + [agents.*] sections
  ├── README.md           # user-facing docs
  ├── SKILL-main.md       # Librarian (coordinator) routing + FS ops
  ├── SKILL-ingestor.md   # Source extraction + [[wikilink]] writing
  ├── SKILL-analyst.md    # Synthesis with provenance citations
  └── SKILL-linter.md     # Broken link / orphan / contradiction audit

Closes librefang/librefang-registry#44 (via replay, not merge).

hands/wiki/SKILL-linter.md

@@ -0,0 +1,95 @@
+---
+name: wiki-linter
+version: "1.0.0"
+description: Wiki Linter skills — structural checks, provenance validation, contradiction detection, and vault health.
+author: Leszek3737
+tags: [wiki, knowledge-base, linter, validation, quality]
+runtime: prompt_only
+---
+
+# Wiki Hand — SKILL-linter.md
+
+## 1. Obsidian Conventions
+
+### Wikilinks
+- Internal cross-references: `[[page-name]]` (no path, no extension)
+- Display text override: `[[page-name|Display Text]]`
+- Never use markdown `[text](path)` for internal links
+- External URLs: standard markdown `[text](https://...)`
+- Image embeds: `![[filename.png]]`
+- Images live in `raw/assets/`
+
+### File Naming
+- Format: `kebab-case.md`
+- Max 40 characters (excluding `.md`)
+- ASCII only — transliterate non-ASCII characters (ü → ue, ñ → n, ś → s, etc.)
+- Entities: canonical name (`john-doe.md`, not `dr-john-doe-phd.md`)
+- Concepts: noun phrase (`knowledge-base.md`, not `about-knowledge-bases.md`)
+- Sources: derived from title (`the-future-of-ai.md`)
+- Syntheses: derived from query (`tradeoffs-x-vs-y.md`)
+- No version suffixes (_v2, _revised, _updated)
+
+### Frontmatter
+- Valid YAML between `---` delimiters at the top of every page
+- All fields lowercase with underscores
+- Dates: ISO 8601 (`YYYY-MM-DD`)
+- Lists: YAML sequences (not comma-separated strings)
+- Dataview-compatible: all fields are queryable
+
+### Dataview Compatibility
+Useful queries the user can run in Obsidian:
+```dataview
+TABLE confidence, source_count, last_updated
+FROM "pages/entities"
+SORT source_count DESC
+```
+```dataview
+LIST
+FROM "pages/concepts"
+WHERE confidence = "disputed"
+```
+```dataview
+TABLE claim_count, date_ingested
+FROM "pages/sources"
+SORT date_ingested DESC
+```
+
+---
+
+## 8. Lint Checks Reference
+
+### Check Definitions
+
+| Check | Severity | Method |
+|-------|----------|--------|
+| Missing frontmatter | critical | Parse YAML — absent or malformed |
+| Missing required field | critical | Compare against schema.md |
+| Dead wikilink | critical | `find pages/ -name "{name}.md"` for each [[link]] |
+| No provenance tag | critical | Scan Key Claims/Points/Facts bullets for missing tag |
+| Index/file mismatch | critical | Compare index.md entries with actual files |
+| Orphan page | warning | `grep -rl` across ALL pages/ for inbound links |
+| Contradiction | warning | Compare extracted claims across pages sharing tags |
+| Stale content | warning | `last_updated` vs newest source's `date_ingested` |
+| Weak provenance | warning | `(inferred)` with source_count=1, or `high` confidence with source_count<2 |
+| Duplicate filenames | warning | Fuzzy match on filenames (e.g., acme-corp + acme-corporation) |
+| File not in index | warning | File exists but no index.md entry |
+| Missing page | info | Plain-text entity/concept in 3+ source summaries |
+| Large page | info | Word count > 3000 |
+
+### Auto-Fixable vs Requires Confirmation
+
+**Auto-fixable** (Librarian applies directly):
+- Missing `last_updated` → set to today
+- File missing from index.md → add entry with description from page's first paragraph
+- Index entry without corresponding file → remove entry
+
+**Requires user confirmation:**
+- Contradictions (user decides which claim is correct)
+- Merge recommendations (user reviews combined content)
+- Delete recommendations (user accepts information loss)
+- Confidence changes (user validates reasoning)
+- New page creation (user approves topic importance)
+
+---
+
+## 12. Worked Examples