fix: prevent spurious container recreation on every start

The CLAUDE_INSTRUCTIONS env var was computed differently during container
creation (with port mapping docs + scheduler instructions appended) vs
the recreation check (bare merge only). This caused
container_needs_recreation() to always return true, triggering a full
recreate on every stop/start cycle.

Extract build_claude_instructions() helper used by both code paths so
the expected value always matches what was set at creation time.

Also add TODO.md noting planned tauri-plugin-updater integration for
seamless in-app updates on all platforms.

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

TODO.md

@@ -0,0 +1,60 @@
+# TODO / Future Improvements
+
+## In-App Auto-Update via `tauri-plugin-updater`
+
+**Priority:** High
+**Status:** Planned
+
+Currently the app detects available updates via the Gitea API (`check_for_updates` command) but cannot apply them. Users must manually download and install the new version. On macOS and Linux this is a poor experience compared to Windows (where NSIS handles upgrades cleanly).
+
+### Recommended approach: `tauri-plugin-updater`
+
+Full in-app auto-update: detects, downloads, verifies, and applies updates seamlessly on all platforms. The user clicks "Update" and the app restarts with the new version.
+
+### Requirements
+
+1. **Generate a Tauri update signing key pair** (this is Tauri's own Ed25519 key, not OS code signing):
+   ```bash
+   npx @tauri-apps/cli signer generate -w ~/.tauri/triple-c.key
+   ```
+   Set `TAURI_SIGNING_PRIVATE_KEY` and `TAURI_SIGNING_PRIVATE_KEY_PASSWORD` in CI.
+
+2. **Add `tauri-plugin-updater`** to Rust and JS dependencies.
+
+3. **Create an update endpoint** that returns Tauri's expected JSON format:
+   ```json
+   {
+     "version": "v0.1.100",
+     "notes": "Changelog here",
+     "pub_date": "2026-03-01T00:00:00Z",
+     "platforms": {
+       "darwin-x86_64": { "signature": "...", "url": "https://..." },
+       "darwin-aarch64": { "signature": "...", "url": "https://..." },
+       "linux-x86_64": { "signature": "...", "url": "https://..." },
+       "windows-x86_64": { "signature": "...", "url": "https://..." }
+     }
+   }
+   ```
+   This could be a static JSON file uploaded alongside release assets, or a small API that reads from Gitea releases and reformats.
+
+4. **Configure the updater** in `tauri.conf.json`:
+   ```json
+   "plugins": {
+     "updater": {
+       "endpoints": ["https://repo.anhonesthost.net/...update-endpoint..."],
+       "pubkey": "<public key from step 1>"
+     }
+   }
+   ```
+
+5. **Add frontend UI** for the update prompt (replace or enhance the existing update check flow).
+
+6. **Update CI pipeline** to:
+   - Sign bundles with the Tauri key during build
+   - Upload `.sig` files alongside installers
+   - Generate/upload the update endpoint JSON
+
+### References
+- https://v2.tauri.app/plugin/updater/
+- Existing update check code: `app/src-tauri/src/commands/update_commands.rs`
+- Existing models: `app/src-tauri/src/models/update_info.rs`