feat(llm-aliases): M5 — migrate consumers to MANA_LLM aliases

Final milestone of docs/plans/llm-fallback-aliases.md. Every backend
caller now requests models via the `mana/<class>` alias system instead
of hardcoded `ollama/...` strings. mana-llm resolves aliases through
`services/mana-llm/aliases.yaml` with health-aware fallback (M3) and
emits resolved-model + fallback metrics (M4).

SSOT moved to `packages/shared-ai/src/llm-aliases.ts` so apps/api,
apps/mana/apps/web, and services/mana-ai all import the same
`MANA_LLM` constant via the existing `@mana/shared-ai` workspace
dependency. Three additional sites (memoro-server, mana-events,
mana-research) inline the alias string with a SSOT comment because
they don't pull @mana/shared-ai today.

Migrated 14 sites across 10 files:
- apps/api: writing(LONG_FORM), comic(STRUCTURED), context(FAST_TEXT),
  food(VISION), plants(VISION), research orchestrator (3 tiers
  collapsed to STRUCTURED+FAST_TEXT/LONG_FORM)
- apps/mana/apps/web: voice/parse-task + parse-habit (STRUCTURED)
- services/mana-ai: planner llm-client + tick.ts (REASONING)
- services/mana-events: website-extractor (STRUCTURED, inlined)
- services/mana-research: mana-llm client (FAST_TEXT, inlined)
- apps/memoro/apps/server: ai.ts (FAST_TEXT, inlined)

Legacy env-vars removed: WRITING_MODEL, COMIC_STORYBOARD_MODEL,
VISION_MODEL, MANA_LLM_DEFAULT_MODEL. The chain in aliases.yaml is
now the single tuning surface; SIGHUP reloads it without redeploys.

New `scripts/validate-llm-strings.mjs` regex-scans 2538 files for
hardcoded `<provider>/<model>` strings and fails the build if any
land outside the SSOT or the explicitly-allowed paths (image-gen
modules, model-inspector code, this validator itself, the registry).
Wired into `validate:all` next to the i18n + theme validators.

Verified: `pnpm validate:llm-strings` clean, `pnpm --filter @mana/api
type-check` clean, `pnpm --filter @mana/ai-service type-check`
clean. Web type-check has 2 pre-existing errors in
SettingsSidebar.svelte (i18n MessageFormatter type drift, last
touched in 988c17a67 — unrelated to this work).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/memoro/apps/server/src/lib/ai.ts

@@ -7,9 +7,14 @@
  *   3. Azure OpenAI (Microsoft Cloud)
  */
 
-// Self-hosted mana-llm service
+// Self-hosted mana-llm service. Use the `mana/<class>` alias system —
+// see packages/shared-ai/src/llm-aliases.ts and
+// services/mana-llm/aliases.yaml for the SSOT and the resolution chain.
+// (memoro-server doesn't pull @mana/shared-ai as a workspace dep yet,
+// so the alias string is inlined here. If memoro adds more LLM call
+// sites, fold this into a workspace import.)
 const MANA_LLM_URL = process.env.MANA_LLM_URL || '';
-const MANA_LLM_MODEL = process.env.MANA_LLM_MODEL || 'ollama/gemma3:4b';
+const MANA_LLM_MODEL = process.env.MANA_LLM_MODEL || 'mana/fast-text';
 
 // Gemini (cloud fallback)
 const GEMINI_ENDPOINT = 'https://generativelanguage.googleapis.com/v1beta/models';