Upgrade pg-boss from 10 to 12

Supersedes dependabot #264 — this one involves code changes that PR
couldn't make.

## Breaking changes in our usage surface

### v12: default export removed → named `PgBoss` export

Affects every file that imports the SDK:
- `packages/jobs/src/boss.ts`: `import PgBoss` → `import { PgBoss }`
- `packages/jobs/src/worker.ts`: same for the type import
- `packages/jobs/src/types.ts`: `PgBoss.Job<T>` → `Job<T>` (types.ts
  re-exports `Job` at the package root in v12)

### v11: queue names restricted to `[A-Za-z0-9_.-]`

Colon `:` is no longer allowed. Renamed the two journal queues that
had it:
- `demo-bot:generate` → `demo-bot-generate`
- `demo-bot:prune`    → `demo-bot-prune`

The planner's `expire-sessions` was already valid.

### v12: minimum Node 22.12

Not a code change for us — journal + planner Dockerfiles are on
`node:25-slim`, CI runners on 24.

## Regression guard

Added `assertValidJobName()` in `@trails-cool/jobs`, called by
`startWorker()` before any side effects. Pg-boss v11+ silently accepts
an invalid name then rejects the underlying SQL call later — we fail
loudly at boot instead. Unit tests cover the character-class rule
and exercise the exact old-name (`demo-bot:generate`) as a
regression fence.

## Prod rollout note

Pg-boss v11 dropped the auto-migration path from v10. On deploy, the
live `pgboss` schema from v10 won't migrate cleanly. Simplest path:
`DROP SCHEMA pgboss CASCADE` before the first v12 worker starts —
our jobs are all cron-scheduled and will re-register themselves on
boot, so there's nothing durable to preserve in the queue.

## Verified

- `pnpm typecheck` / `pnpm lint` / `pnpm test` — all clean
- `pnpm exec playwright test --workers=2` — 50/50 passed

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

apps/journal/app/jobs/demo-bot-generate.ts

@@ -22,7 +22,7 @@ import { logger } from "../lib/logger.server.ts";
  *    daily cap; on pass, insert one route+activity via `generateOneWalk`.
  */
 export const demoBotGenerateJob: JobDefinition = {
-  name: "demo-bot:generate",
+  name: "demo-bot-generate",
   cron: "0,30 * * * *",
   retryLimit: 1,
   expireInSeconds: 120,

apps/journal/app/jobs/demo-bot-prune.ts

@@ -12,7 +12,7 @@ import { logger } from "../lib/logger.server.ts";
  * `DEMO_BOT_RETENTION_DAYS` (default 14). Never touches real users.
  */
 export const demoBotPruneJob: JobDefinition = {
-  name: "demo-bot:prune",
+  name: "demo-bot-prune",
   cron: "15 3 * * *",
   retryLimit: 1,
   expireInSeconds: 60,