feat(mcp): advertise output schemas for data tools + bump to v1.22

[felixgeelhaar]

What

Adopts mcp-go structured content for scout's fixed-schema data tools. Each converted tool now emits typed `structuredContent` alongside its JSON text block via `ToolBuilder.OutputSchema`, following the in-repo precedent already set by `observe`, `network_summary`, and `aria_violations`.

Folds in the pending mcp bump v1.21 -> v1.22 — supersedes #64. Built clean, no auth usage.

Tools converted

Object-returning tools (added `.OutputSchema(T{})`, no behavior change — they already returned typed structs):

Tool	Output type
`network_requests`	`NetworkRequestsResult`
`web_vitals`	`agent.WebVitalsResult`
`console_errors`	`agent.DiagnosticsResult`
`check_readiness`	`agent.PageReadiness`
`discover_form`	`agent.FormDiscoveryResult`

Bare-slice tools wrapped in a fixed `{items, total}` object envelope (structuredContent must be a JSON object, not a bare array — each element is a fixed-shape struct):

Tool	Envelope	Element type
`failed_requests`	`FailedRequestsResult`	`agent.NetworkFailure`
`list_tabs`	`ListTabsResult`	`agent.TabInfo`
`cookies_list`	`CookiesListResult`	`agent.CookieInfo`

Already advertised (left untouched): `network_summary`, `aria_violations`.

Intentionally skipped — cannot honor a fixed schema

• `accessibility_tree` — returns a plain `string` (compact text tree), not a JSON object; nothing fixed to advertise.
• `component_state`, `app_state` — return `map[string]any`; the shape is framework/page-dependent, so a fixed OutputSchema would be a contract scout can't keep.
• Dynamic-extraction tools (`extract`, `extract_all`, `auto_extract`, `markdown`, `readable_text`, `observe*`, `scroll_and_collect`) and all browser-action / mutation tools — out of scope; their output depends on the page/selector.

Guard test

Adds `TestOutputSchemasGenerate` (`cmd/scout/mcp_outputschema_test.go`): calls `schema.Generate` for every advertised output type. `OutputSchema` runs `schema.Generate` at registration and silently drops the tool if it errors — this test fails loudly in CI instead, so a type that becomes unrepresentable is caught rather than silently removing a production tool.

Verification

• `gofmt -l` on changed files: clean
• `go build ./...`: exit 0
• `go vet ./...`: clean
• `go test ./... -count=1`: all pass
• `golangci-lint run ./cmd/scout/`: 0 issues

https://claude.ai/code/session_01LCyhyAffdzBmzG3yPPqzTT