deps: bump rmcp from 1.7.0 to 3.1.2

[dependabot]

Bumps rmcp from 1.7.0 to 3.1.2.

Release notes

Sourced from rmcp's releases.

rmcp-macros-v3.1.2

Fixed

• emit cache hints from handler macros (#1120)

Other

• upgrade darling and syn (#1138)

rmcp-v3.1.2

Fixed

• (auth) map 401/403 challenges on the SSE GET stream (#1152)
• (sse) loop instead of recursing when skipping SSE events (#1146)
• (auth) preserve issuer trailing slash during discovery (#1145)

rmcp-macros-v3.1.1

Fixed

• emit cache hints from handler macros (#1120)

Other

• upgrade darling and syn (#1138)

rmcp-v3.1.1

Fixed

• emit cache hints from handler macros (#1120)
• expose MRTR state to tool handlers (#1104)
• disambiguate input-required results (#1103)

Other

• make async-trait optional (#1119)

rmcp-macros-v3.1.0

Added

• add strict stateless protocol metadata validation (#1091)

Other

• document the ping utility with examples (#1106)
• complete Tier 1 feature docs and finalize roadmap (#1101)
• (conformance) meeting requirements for tier 1 (#1087)

rmcp-v3.1.0

Added

... (truncated)

Commits

• 02c62ae chore: release v3.1.2 (#1148)
• c345078 fix(auth): map 401/403 challenges on the SSE GET stream (#1152)
• f8e6382 chore(deps): bump taiki-e/install-action from 2.85.7 to 2.85.8 (#1153)
• 8fb3e04 chore(deps): bump github/codeql-action from 4.37.4 to 4.37.6 (#1154)
• 3c8fb2a fix(sse): loop instead of recursing when skipping SSE events (#1146)
• e150d4f fix(auth): preserve issuer trailing slash during discovery (#1145)
• 9a3168a chore(deps): bump taiki-e/install-action from 2.85.6 to 2.85.7 (#1139)
• baac607 chore: release v3.1.1 (#1115)
• f57d585 chore: upgrade darling and syn (#1138)
• 07bcda2 fix: emit cache hints from handler macros (#1120)
• Additional commits viewable in compare view

[OrellBuehler]

Superseded by #34, which does the actual migration — rmcp 3 renamed Content to ContentBlock and added inbound Host validation, so the lockfile-only bump here does not compile and would have made every KERF_MCP_ADDR override reject its own clients.

Landed on rmcp 3.1.4 with a derived host allow-list, tests pinning the tool-schema contract across the schemars 0.8 → 1.x switch, and a Windows manifest fix the upgrade turned up.

[dependabot]

OK, I won't notify you again about this release, but will get in touch when a new version is available. If you'd rather skip all updates until the next major or minor version, let me know by commenting @dependabot ignore this major version or @dependabot ignore this minor version. You can also ignore all major, minor, or patch releases for a dependency by adding an ignore condition with the desired update_types to your config file.

If you change your mind, just re-open this PR and I'll resolve any conflicts on it.