Skills engine v0.1 + multi-channel infrastructure (#307)

* refactor: multi-channel infrastructure with explicit channel/is_group tracking

- Add channels[] array and findChannel() routing in index.ts, replacing
  hardcoded whatsapp.* calls with channel-agnostic callbacks
- Add channel TEXT and is_group INTEGER columns to chats table with
  COALESCE upsert to protect existing values from null overwrites
- is_group defaults to 0 (safe: unknown chats excluded from groups)
- WhatsApp passes explicit channel='whatsapp' and isGroup to onChatMetadata
- getAvailableGroups filters on is_group instead of JID pattern matching
- findChannel logs warnings instead of silently dropping unroutable JIDs
- Migration backfills channel/is_group from JID patterns for existing DBs

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: skills engine v0.1 — deterministic skill packages with rerere resolution

Three-way merge engine for applying skill packages on top of a core
codebase. Skills declare which files they add/modify, and the engine
uses git merge-file for conflict detection with git rerere for
automatic resolution of previously-seen conflicts.

Key components:
- apply: three-way merge with backup/rollback safety net
- replay: clean-slate replay for uninstall and rebase
- update: core version updates with deletion detection
- rebase: bake applied skills into base (one-way)
- manifest: validation with path traversal protection
- resolution-cache: pre-computed rerere resolutions
- structured: npm deps, env vars, docker-compose merging
- CI: per-skill test matrix with conflict detection

151 unit tests covering merge, rerere, backup, replay, uninstall,
update, rebase, structured ops, and edge cases.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* feat: add Discord and Telegram skill packages

Skill packages for adding Discord and Telegram channels to NanoClaw.
Each package includes:
- Channel implementation (add/src/channels/)
- Three-way merge targets for index.ts, config.ts, routing.test.ts
- Intent docs explaining merge invariants
- Standalone integration tests
- manifest.yaml with dependency/conflict declarations

Applied via: npx tsx scripts/apply-skill.ts .claude/skills/add-discord
These are inert until applied — no runtime impact.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

* remove unused docs (skills-system-status, implementation-guide)

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

.claude/skills/add-telegram/modify/src/config.ts.intent.md

@@ -0,0 +1,21 @@
+# Intent: src/config.ts modifications
+
+## What changed
+Added two new configuration exports for Telegram channel support.
+
+## Key sections
+- **readEnvFile call**: Must include `TELEGRAM_BOT_TOKEN` and `TELEGRAM_ONLY` in the keys array. NanoClaw does NOT load `.env` into `process.env` — all `.env` values must be explicitly requested via `readEnvFile()`.
+- **TELEGRAM_BOT_TOKEN**: Read from `process.env` first, then `envConfig` fallback, defaults to empty string (channel disabled when empty)
+- **TELEGRAM_ONLY**: Boolean flag from `process.env` or `envConfig`, when `true` disables WhatsApp channel creation
+
+## Invariants
+- All existing config exports remain unchanged
+- New Telegram keys are added to the `readEnvFile` call alongside existing keys
+- New exports are appended at the end of the file
+- No existing behavior is modified — Telegram config is additive only
+- Both `process.env` and `envConfig` are checked (same pattern as `ASSISTANT_NAME`)
+
+## Must-keep
+- All existing exports (`ASSISTANT_NAME`, `POLL_INTERVAL`, `TRIGGER_PATTERN`, etc.)
+- The `readEnvFile` pattern — ALL config read from `.env` must go through this function
+- The `escapeRegex` helper and `TRIGGER_PATTERN` construction