feat(auth): revocable API tokens, introspect MCP server, and a Go 1.26 idiom pass (#1266)

* feat(auth): add revocable API tokens (bot/service auth)

Add long-lived, revocable API tokens so headless clients (the introspection
MCP tool, bots, CI) can authenticate without a password. Presented as
"Authorization: Bearer <token>", a token authenticates as a specific user,
inheriting that user's role and permissions.

- migration 018 + dedicated api_tokens table (kept separate from sessions so
  bulk logout and the per-user session cap never touch these); only the
  SHA-256 hash is stored, raw token shown once at creation
- auth.ResolveTokenHash: one shared bearer resolver that both AuthMiddleware
  and adminAuthMiddleware now call. Sessions are matched first so existing
  login behavior is unchanged; API tokens are a fallback only on session miss.
  A DB outage is returned wrapped, never mistaken for a bad token.
- `server token create|list|revoke` CLI: mints directly against the DB with no
  HTTP and no login — the password-free bootstrap path
- tests: resolver (8 cases incl. outage-not-fallthrough), db queries (6),
  api middleware integration (valid + revoked token)

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* feat(tools): add owncord-introspect MCP server

A local MCP dev tool that lets Claude Code introspect a running OwnCord
instance: read its logs, query any REST endpoint, and tail the desktop
client's log file. It is a thin wrapper over the existing API plus the
client log — no new product surface.

- tools/mcp-introspect/index.mjs (Node/ESM, one dep: @modelcontextprotocol/sdk)
  exposes api_request (full read-write passthrough), server_logs (admin SSE
  ring-buffer stream), client_logs (reads the desktop log file)
- authenticates with an API token (OWNCORD_API_TOKEN); pins the self-signed
  cert and skips hostname checks (the cert has no SAN)
- registered in .mcp.json (secret-free ${OWNCORD_API_TOKEN})
- un-ignore tools/mcp-introspect/ so this shared dev tool is committed, while
  tools/livekit-server.exe and node_modules stay ignored
- docs/mcp-introspect.md: how it works, tool reference, setup, troubleshooting

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* feat(dependencies): update and add various crate versions in Cargo.lock

* feat(admin): manage API tokens from the admin panel

Add Owner-gated HTTP endpoints and a UI card to create, list, and revoke
API tokens from the web admin panel. Previously only the `server token`
CLI could manage them, which requires shell access to the host.

- POST|GET|DELETE /admin/api/tokens in admin/handlers_tokens.go, wired in
  admin/api.go. All three are Owner-only (ownerOnlyMiddleware, like
  backups/updates): an HTTP token-mint endpoint is a network-reachable
  credential-minting surface, and API tokens deliberately survive password
  change + bulk logout, so a hijacked admin session must not mint one.
- Reuses the same db.*APIToken calls as the CLI; create sources the actor
  from request context (audits who clicked, not the bound user); the raw
  token is returned once in the 201 body, never stored.
- Add json tags to db.APITokenListItem for snake_case wire consistency.
- Admin panel: "API Tokens" nav item + create modal, show-once reveal,
  revoke confirm in admin/static/index.html.
- Tests: 7 in admin/api_test.go (+api_tokens table in the in-memory schema).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

* refactor: modernize to Go 1.26 idioms + enable modernize linter

Apply `golangci-lint modernize` autofixes across the server and enable the
linter in .golangci.yml so these stop re-accumulating (they built up only
because modernize was never in the config).

Production code: slices.Contains for hand-rolled membership loops (api
router, ws origin, db/account, plugin manifest); strings.SplitSeq for
allocation-free line/segment iteration (db/migrate, updater, livekit_proxy);
strings.Cut (config); fmt.Appendf (dm_handler); min() (event_pruner);
any (ws client). Tests: range-over-int, t.Context(), WaitGroup.Go,
slices.Sort, maps.Copy, new(expr), interface{}->any.

- plugin/manifest.go parent-traversal check applied by hand: modernize
  skipped it (two conflicting rewrites); used the slices.Contains form.
- Removed the now-dead ptr() test helper after newexpr inlined its callers.
- Dropped dangling sort imports left by the sort.Slice->slices.Sort rewrite.

No behavior change. All four tag variants build, full test suite is green,
and golangci-lint (with modernize enabled) reports 0 issues.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

docs/schema.md

@@ -60,6 +60,7 @@ CREATE TABLE IF NOT EXISTS schema_versions (
 | `015_plugins.sql` | Adds `plugins` and `plugin_kv` for the WASM plugin runtime |
 | `016_announcement_channel_type.sql` | Recreates the channel-type triggers to allow `announcement` |
 | `017_user_identity_key.sql` | Adds `users.identity_public_key` (long-term E2EE identity key for voice TOFU) |
+| `018_api_tokens.sql` | Adds `api_tokens` — long-lived, revocable bearer tokens for headless clients (bot/service auth) |
 
 ---
 
@@ -138,6 +139,30 @@ Session TTL: 30 days. Token is stored as SHA-256 hash.
 
 ---
 
+### api_tokens
+
+```sql
+CREATE TABLE api_tokens (
+    id           INTEGER PRIMARY KEY AUTOINCREMENT,
+    user_id      INTEGER NOT NULL REFERENCES users(id) ON DELETE CASCADE,
+    token_hash   TEXT    NOT NULL UNIQUE,
+    label        TEXT    NOT NULL DEFAULT '',
+    created_at   TEXT    NOT NULL DEFAULT (datetime('now')),
+    last_used_at TEXT,
+    expires_at   TEXT,
+    revoked_at   TEXT
+);
+```
+
+Long-lived, revocable bearer tokens for headless clients (bots, CI, the introspection
+MCP tool). A token authenticates as `user_id`, inheriting that user's role/permissions,
+and is resolved by the same middleware as sessions (see `auth.ResolveTokenHash`). Only the
+SHA-256 hash is stored; the raw token is shown once at creation. `expires_at` NULL = never
+expires; `revoked_at` NULL = active. Mint/list/revoke via `server token …`. Separate from
+`sessions` so bulk logout and the per-user session cap never affect these.
+
+---
+
 ### channels
 
 ```sql