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>

skills-engine/types.ts

@@ -0,0 +1,134 @@
+export interface SkillManifest {
+  skill: string;
+  version: string;
+  description: string;
+  core_version: string;
+  adds: string[];
+  modifies: string[];
+  structured?: {
+    npm_dependencies?: Record<string, string>;
+    env_additions?: string[];
+    docker_compose_services?: Record<string, unknown>;
+  };
+  file_ops?: FileOperation[];
+  conflicts: string[];
+  depends: string[];
+  test?: string;
+  author?: string;
+  license?: string;
+  min_skills_system_version?: string;
+  tested_with?: string[];
+  post_apply?: string[];
+}
+
+export interface SkillState {
+  skills_system_version: string;
+  core_version: string;
+  applied_skills: AppliedSkill[];
+  custom_modifications?: CustomModification[];
+  path_remap?: Record<string, string>;
+  rebased_at?: string;
+}
+
+export interface AppliedSkill {
+  name: string;
+  version: string;
+  applied_at: string;
+  file_hashes: Record<string, string>;
+  structured_outcomes?: Record<string, unknown>;
+  custom_patch?: string;
+  custom_patch_description?: string;
+}
+
+export interface ApplyResult {
+  success: boolean;
+  skill: string;
+  version: string;
+  mergeConflicts?: string[];
+  backupPending?: boolean;
+  untrackedChanges?: string[];
+  error?: string;
+}
+
+export interface MergeResult {
+  clean: boolean;
+  exitCode: number;
+}
+
+export interface FileOperation {
+  type: 'rename' | 'delete' | 'move';
+  from?: string;
+  to?: string;
+  path?: string;
+}
+
+export interface FileOpsResult {
+  success: boolean;
+  executed: FileOperation[];
+  warnings: string[];
+  errors: string[];
+}
+
+export interface CustomModification {
+  description: string;
+  applied_at: string;
+  files_modified: string[];
+  patch_file: string;
+}
+
+export interface FileInputHashes {
+  base: string;     // SHA-256 of .nanoclaw/base/<relPath>
+  current: string;  // SHA-256 of working tree <relPath> before this merge
+  skill: string;    // SHA-256 of skill's modify/<relPath>
+}
+
+export interface ResolutionMeta {
+  skills: string[];
+  apply_order: string[];
+  core_version: string;
+  resolved_at: string;
+  tested: boolean;
+  test_passed: boolean;
+  resolution_source: 'maintainer' | 'user' | 'claude';
+  input_hashes: Record<string, string>;
+  output_hash: string;
+  file_hashes: Record<string, FileInputHashes>;
+}
+
+export interface UpdatePreview {
+  currentVersion: string;
+  newVersion: string;
+  filesChanged: string[];
+  filesDeleted: string[];
+  conflictRisk: string[];
+  customPatchesAtRisk: string[];
+}
+
+export interface UpdateResult {
+  success: boolean;
+  previousVersion: string;
+  newVersion: string;
+  mergeConflicts?: string[];
+  backupPending?: boolean;
+  customPatchFailures?: string[];
+  skillReapplyResults?: Record<string, boolean>;
+  error?: string;
+}
+
+export interface UninstallResult {
+  success: boolean;
+  skill: string;
+  customPatchWarning?: string;
+  replayResults?: Record<string, boolean>;
+  error?: string;
+}
+
+export interface RebaseResult {
+  success: boolean;
+  patchFile?: string;
+  filesInPatch: number;
+  rebased_at?: string;
+  mergeConflicts?: string[];
+  backupPending?: boolean;
+  error?: string;
+}