feat(repos): complete typed repository tool outputs

[SamMorrowDrums]

Summary

Complete the remaining 17 typed MCP tools in pkg/github/repositories.go, using the existing protocol-gated NewTool[In, Out] foundation. Modern clients receive concrete output schemas and structured content; legacy/unknown clients retain their original content without output schemas or structured content.

Why

Continue the file-focused typed-tool migration, stacked on #3391. No issue is closed by this slice.
Fixes # N/A

Exact parent/base: 7b0c05e0eae079b0a973d44ea73f6244a491b2a0 (sammorrowdrums-type-core-issue-tools), based on repository layer 4b6686b5fc361a702e50d7e37a55870e49da6900. The original parent 01770e05065e86a964af3bc7834ebded7f03ed1e and original repository ancestor 79f584df3f05c756e97904016e70985731fb6f77 were verified before edits; the refreshed parent was synchronized safely before final validation.
Exact slice head: 7e864d1e6c4eaadc2050c9d7d973d123471e4ea8.

What changed

• Concrete inputs/outputs for create_or_update_file, create_repository, delete_repository, get_file_contents, fork_repository, delete_file, create_branch, push_files, get_tag, list_releases, get_latest_release, get_release_by_tag, list_starred_repositories, star_repository, unstar_repository, get_file_blame, and list_repository_collaborators.
• Preserve the existing get_commit, list_commits, list_branches, and list_tags migrations. Retain scopes, workflow challenges, feature gates, IFC labeling, sanitization, field filtering, deletion confirmation, and mutation behavior.
• Infer honest SDK schemas from real concrete API DTOs; timestamp and recursive Git/user/team types use precise inferred definitions and references, not opaque maps. Strict unions cover tag references/annotated tags, fork references/in-progress messages, and directory/content responses. Null union states support SDK error serialization; tool errors do not expose structured output.
• Preserve file status text and multiple MCP content blocks. File/resource/blob/link and metadata-only responses are represented by a typed content array; directory projections remain structured arrays. Text-only mutations use a structured message matching the actual status response.
• Add modern/legacy/unknown wire tests, all 17 negotiated schemas, strict union rejection, realistic release/commit objects, byte-exact content-block comparisons, empty file/directory/range outputs, pagination coercion/defaults, projections, API/domain errors, mutation request assertions, and deletion confirmation coverage.

MCP impact

• No tool or API changes
• Tool schema or behavior changed
• New tool added

Output schemas and typed structuredContent are exposed only for protocol 2026-07-28 and newer. Existing content remains unchanged; legacy/unknown protocol clients receive neither output schemas nor structured content.

Prompts tested (tool changes only)

• Automated wire equivalents: "Create a private repository; create a file and branch; push an empty file; delete a file; star/unstar a repository."
• Automated wire equivalents: "Read text, binary, empty, large, symlink, submodule, and directory paths; project directory fields; resolve a missing path."
• Automated wire equivalents: "Get lightweight/annotated tags; list releases with numeric-string and zero/default pagination; project release fields; get a release by tag."
• Automated wire equivalents: "Page file blame and collaborators; confirm repository deletion." No live GitHub mutations were performed.

Security / limits

• No security or limits impact
• Auth / permissions considered
• Data exposure, filtering, or token/size limits considered

Existing scopes, workflow-scope challenges, IFC labels, sanitization, field projections, 1 MiB resource-link behavior, blame limits, and repository deletion confirmation remain in place. Structured file output mirrors the already-returned content; it does not fetch additional data or bypass permissions.

Tool renaming

• I am renaming tools as part of this PR (e.g. a part of a consolidation effort)
  • I have added the new tool aliases in deprecated_tool_aliases.go
• I am not renaming tools as part of this PR

Note: if you're renaming tools, you must add the tool aliases. For more information on how to do so, please refer to the official docs.

Lint & tests

• Linted locally with ./script/lint

• Tested locally with ./script/test

• UPDATE_TOOLSNAPS=true go test ./... — passed; all intended raw/negotiated output schemas snapshotted.

• script/lint — passed.

• script/test — passed (go test -race ./...).

• script/generate-docs — passed.

• git diff --check — passed.

The required lint → race tests → documentation ordering was run on the refreshed exact parent. E2E tests requiring a live GitHub PAT were not run. CI will be inspected after PR creation. License-bot manifests were preserved without changes.

Docs

• Not needed
• Updated (README / docs / examples)

README explains protocol gating and the typed representations of content-only repository responses. Tool schemas include updated snapshots.