fix(server): update commands match a global styal install

[incognitojam]

A styal server installed with npm i -g @styal/cli and started from a terminal was given npx @styal/cli@<version> serve as its update command. That runs the new version once but leaves the installed styal command on the old version, so the update notice comes back on the next launch.

This ports upstream's installation detection from pingdotgg#15539 to styal's npm identity. That upstream commit is already recorded on main without its changes, because its detection only recognized T3 Code's t3 package.

• The server proves a global install from the lib/node_modules/@styal/cli layout:
  • <prefix>/bin/styal must resolve to the running launcher.
  • A running platform executable (@styal/cli-<platform>/styal) must match the launcher's version and its optional dependency.
• The server reports the result, or an npx, pnpm dlx or bunx start, in the optional serverInstallation environment capability.
• For a foreground server, the update instructions in chat, Connections settings and the auto-balance banner now copy:
  • for a proven global install: npm install --global --prefix '<prefix>' @styal/cli@<version>, followed by a note to restart styal;
  • for a runner start: serve through the same runner;
  • for anything unproven, including Windows: the existing npx @styal/cli@<version> serve, with a note that it doesn't update an installed styal command.
• The one-time service migration command is unchanged. Mobile has no manual-command surface.
• The update docs and the server-update-guidance ledger entry are updated.

Validation

• Installed the published @styal/cli into a scratch prefix with npm install --global --prefix. Ran this branch's detection against the installed launcher, the global bin and the @styal/cli-linux-x64/styal executable. It reported {"kind":"npm-global","prefix":"<scratch prefix>"}. The legacy dist/bin.mjs entry correctly reported nothing.
• In a real web client, the server's version was set older than the client's and its installation reported as a global install under /opt/node tools; both were set with a temporary local override that isn't part of this change. The Connections update dialog showed the screenshot above. The prefix was quoted correctly, and Copy is labelled "Copy update command". The screenshot uses a synthetic environment name.
• Focused tests pass, 67 across 5 files. They cover:
  • detection ownership: runner caches; a global bin symlink that is present, missing or unrelated; a native version mismatch; win32; local and standalone installs;
  • descriptor publishing;
  • contract decoding;
  • command formatting, including that the service migration command ignores the installation.
• Contracts, server and web typecheck pass.

These cases behave the same as upstream:

• A root-owned global prefix gets a command that needs sudo.
• Leading or trailing whitespace in a prefix is trimmed by the contract.

---

Written by an agent (Claude Code, claude-opus-5-5).

[github-actions]

Upstream divergence

Both sides are compared with upstream at the in-order tip 06e627448b. Excludes .repos/ and pnpm-lock.yaml.

Measure	Base	This PR	Change
Upstream files the fork changes	1,373	1,373	0
Lines changed in them	64,222	64,046	−176
Upstream files the fork removes	41	41	0
Fork-only files	435	435	0
Fork-only lines	74,641	74,646	+5

Upstream files whose difference changes (13)

File	Change	Now differs by
apps/server/src/cli/invocation.test.ts	−100	92 lines
apps/server/src/cli/invocation.ts	−48	44 lines
apps/server/src/environment/ServerEnvironment.test.ts	−37	11 lines
apps/web/src/versionSkew.test.ts	+27	92 lines
packages/contracts/src/environment.test.ts	−16	8 lines
apps/web/src/components/ServerUpdateAction.tsx	+15	329 lines
docs/user/updating.md	+11	81 lines
packages/contracts/src/environment.ts	−9	12 lines
apps/web/src/versionSkew.ts	−7	53 lines
apps/web/src/components/settings/ConnectionsSettings.tsx	−5	122 lines
apps/server/src/environment/ServerEnvironment.ts	−3	14 lines
apps/web/src/components/ChatView.tsx	−3	775 lines
apps/web/src/components/chat/useAutoBalanceUpdateBanner.tsx	−1	3 lines

[github-actions]

Thread transfer impact

✅ Thread transfer remains within every enforced ceiling.

Provider	Metric	Main baseline	This PR	Impact	PR ceiling
Codex	Total thread wire	5.0 KiB	4.9 KiB	−40 B (−0.8%)	6.8 KiB	✅
Codex	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Codex	Live turn WebSocket wire	1.2 KiB	1.2 KiB	−40 B (−3.3%)	2.0 KiB	✅
Codex	Live turn WebSocket decoded	20.9 KiB	20.8 KiB	−41 B (−0.2%)	29.3 KiB	✅
Codex	Live turn messages	2	1	−1 (−50.0%)	8	✅
Claude	Total thread wire	5.0 KiB	5.0 KiB	0 B (0.0%)	6.8 KiB	✅
Claude	Thread snapshot wire	3.8 KiB	3.8 KiB	0 B (0.0%)	4.9 KiB	✅
Claude	Live turn WebSocket wire	1.2 KiB	1.2 KiB	0 B (0.0%)	2.0 KiB	✅
Claude	Live turn WebSocket decoded	21.2 KiB	21.2 KiB	0 B (0.0%)	29.3 KiB	✅
Claude	Live turn messages	2	2	0 (0.0%)	8	✅

Baseline: 2c68e22 · PR result: b3653e5 · Source CI: success

Scenario and decoded snapshot size

10 historical turns, 5 command tools per turn, 878.9 KiB retained MCP result per historical turn, and a 1.05 MiB retained result in the measured turn.

• Codex decoded thread snapshot: 108.5 KiB
• Claude decoded thread snapshot: 108.8 KiB

Updated in place by a trusted workflow. PR artifacts are strictly validated and never executed.