chore: pin every third-party version a preset installs

[trick77]

Why

opencode resolves a plugin spec once and caches it keyed on the full spec string, then never re-checks:

const directory = (pkg) => path.join(global.cache, "packages", sanitize(pkg))
if (yield* afs.existsSafe(path.join(dir, "node_modules", name)))
  return resolveEntryPoint(...)   // no install, no registry call, no version check

So an unpinned ref is not "tracks latest" — it freezes at whatever resolved on first run, differs per user depending on install date, and can't be named without grepping the cache. Changing the spec string is the only thing that triggers a re-fetch, which makes an explicit pin the only working update path.

@fetch behaved the same way: src/fetch-asset.ts returns a cached file untouched when no sha256= is declared.

Changes

Preset	Before	After
plugin-superpowers	no git ref	#v6.2.0
plugin-litellm-pricing	@0.1.1	@0.2.0
mcp-playwright	@latest	@0.0.78
jdtls-lombok	lombok.jar, no checksum	lombok-1.18.46.jar + sha256=

Notes:

• plugin-litellm-pricing was two releases behind. 0.1.2 fixed a 20-second startup stall; 0.2.0 stopped probing localhost. Commit 00df0c4 had already rewritten this preset's @description for post-0.2.0 behaviour while the pin still shipped 0.1.1.
• mcp-playwright was the only genuinely floating one — npx re-resolves @latest on every MCP server start, so it pulled new unreviewed code into a browser-driving server continuously.
• jdtls-lombok versions the dest filename as well as the URL. fetchAsset returns an existing dest untouched, so reusing lombok.jar would make a future bump a silent no-op. Hash cross-checked against Maven Central: byte-identical jar, matching published sha1, manifest reads Lombok-Version: 1.18.46.

Also: transitive fast-uri 3.1.0 → 3.1.4, clearing four high-severity advisories (path traversal, host confusion ×3); AGENTS.md gains the pinning rule that would have caught this, and its stale "one runtime dep" line is corrected.

Verification

• 101/101 tests pass
• All four install into a temp config with pinned specs; -javaagent path tracks the versioned dest; validate passes
• Re-install is a no-op — preserve 1, no backup written
• remove prunes back to bare $schema
• Appending garbage to the cached jar and re-installing forces a re-download and restores the correct hash, so sha256= is actually enforced rather than merely declared

Out of scope: migrating users who already installed these presets. This changes what new installs resolve to.