chore: upgrade pi to 1.2.0

[Pizzaface]

Summary

Upgrades pi from 1.0.0 to 1.2.0.

• Bumps all @earendil-works/pi-* packages to 1.2.0 in the root and package manifests and in root overrides.
• Removes the overrides for chord, pi-client, pi-protocol and pi-server, which upstream no longer depends on.
• Ports the 4 Bun patches to 1.2.0 with the same hunk count. Six hunks no longer matched upstream and were re-applied with the same changes:
  • pi-ai: Anthropic web_search injection, server-tool passthrough in convertTools, JSON-parse retry patterns.
  • pi-coding-agent: quietStartup defaults to on.
  • pi-tui: Windows console lifecycle.
• hooks/extension.ts: in 1.2, before_agent_start also fires for runs started by pi.sendMessage(..., { triggerTurn: true }). Those events have no prompt, so the hook sends prompt only when messageType === "user".
• Theme $schema now points to https://pi.dev/schemas/theme.schema.json. The theme passes 1.2's new startup validation.
• patches.test.ts: accepts upstream's new SETTINGS_DEFAULTS.quietStartup fallback, which is still false.

Verification

• bun install installs only 1.2.0 pi packages, and coding-agent loads the patched copies of pi-ai and pi-agent-core.
• bun run build and bun run typecheck pass.
• bun run test passes against a throwaway Redis. The first full run failed on the patches.test.ts assertion, which also skipped the UI, docs and mobile tests. After the fix, the CLI stage (214 passed, 0 failed) and every stage after it were re-run and passed. The stages before the CLI stage passed on the first run.

Not changed

• The docs still list the azure-openai-responses API type. Upstream renamed the provider to azure in 1.0.3, but pi-ai still has the azure-openai-responses API type, so I left it.