* fix(server): surface Kiro CLI slash commands and skills over ACP
Kiro CLI advertises its slash commands and skills through the
`_kiro.dev/commands/available` ACP extension notification rather than the
standard `available_commands_update` session update. ACPAgentSession only
trace-logged extension notifications and dropped the payload, so the
composer never showed any Kiro commands or skills.
- Map the extension payload onto the shared slash-command cache:
`commands` (built-in, names arrive with a leading "/") and `prompts`
(skills/prompts, tagged with a `skill:` serverName) are normalized to
Paseo's AgentSlashCommand shape, stripping the leading slash and pulling
the argument hint from `meta.hint`.
- Add KiroACPAgentClient (mirrors CursorACPAgentClient) so the provider
waits for the first async command batch before listCommands() resolves,
since Kiro emits the notification shortly after session/new.
* fix(server): settle on empty Kiro batch; inject Kiro commands via constructor option
Addresses review feedback on #1792.
Keep vendor-specific providers out of the generic acp-agent.ts, following
the same pattern as Cursor/Copilot: provider behavior is injected through
ACPAgentClient constructor options rather than special-cased in the base
class. Adds an optional extensionCommandsParser option on the generic ACP
client/session; the base extNotification() invokes it and routes any parsed
commands through a generic applyResolvedCommands() helper. Kiro supplies
parseKiroExtensionCommands (recognizes _kiro.dev/commands/available); the
base class no longer references any Kiro method string or payload shape.
Also fixes an empty-batch hang: applyResolvedCommands() always settles the
initial-commands gate, so a Kiro user with no slash commands no longer
blocks listCommands() for the full 10s timeout. Adds a regression test.
