feat: add token usage tracking, context display, and dynamic context length (#132)

* fix: specify TS_NODE_PROJECT for dev:server script

ts-node/register resolves tsconfig from the entry file upward,
finding the root solution-style tsconfig.json (no compilerOptions).
This causes target to default to ES3, breaking MapIterator spread
syntax (TS2802). Set TS_NODE_PROJECT env var to point to the server
tsconfig which targets ES2024.

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

* feat: add token usage tracking, context display, and dynamic context length

- Intercept SSE proxy to capture run.completed events and persist token
  usage (input_tokens, output_tokens) per session to SQLite/JSON store
- Display context usage bar in ChatInput showing used/total/remaining tokens
- Resolve actual context length from Hermes models_dev_cache.json based
  on the active profile's default model (fallback 200K), with 5min in-memory cache
- Move sessions-db.ts to db/hermes/ for unified database layer
- Add usage store with SQLite + JSON fallback (auto-migration via ensureTable)
- Fix proxy SSE path regex to match rewritten upstream path
- Fix route ordering: /sessions/usage before /sessions/:id to avoid 404
- Fetch per-session usage on session enter instead of batch
- Add unit tests for usage-store, db index, and proxy SSE interception

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

---------

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

tests/server/sessions-routes.test.ts

@@ -7,6 +7,9 @@ const searchMock = vi.fn(async (ctx: any) => { ctx.body = { results: [{ id: 'sea
 const getMock = vi.fn(async (ctx: any) => { ctx.body = { session: { id: ctx.params.id } } })
 const removeMock = vi.fn(async (ctx: any) => { ctx.body = { ok: true } })
 const renameMock = vi.fn(async (ctx: any) => { ctx.body = { ok: true } })
+const usageBatchMock = vi.fn(async (ctx: any) => { ctx.body = {} })
+const usageSingleMock = vi.fn(async (ctx: any) => { ctx.body = { input_tokens: 0, output_tokens: 0 } })
+const contextLengthMock = vi.fn(async (ctx: any) => { ctx.body = { context_length: 200000 } })
 
 vi.mock('../../packages/server/src/controllers/hermes/sessions', () => ({
   listConversations: listConversationsMock,
@@ -16,6 +19,9 @@ vi.mock('../../packages/server/src/controllers/hermes/sessions', () => ({
   get: getMock,
   remove: removeMock,
   rename: renameMock,
+  usageBatch: usageBatchMock,
+  usageSingle: usageSingleMock,
+  contextLength: contextLengthMock,
 }))
 
 describe('session routes', () => {
@@ -40,7 +46,10 @@ describe('session routes', () => {
       '/api/hermes/sessions',
       '/api/hermes/search/sessions',
       '/api/hermes/sessions/search',
+      '/api/hermes/sessions/usage',
+      '/api/hermes/sessions/context-length',
       '/api/hermes/sessions/:id',
+      '/api/hermes/sessions/:id/usage',
       '/api/hermes/sessions/:id/rename',
     ]))
   })