feat(browser): network --filter <fields> for agent-native request discovery

[jackwener]

Summary

Agents on a page with a wall of network requests know which fields a target request's body should carry (e.g. author, text, likes) but not which of the captured requests is the one. This adds opencli browser network --filter <fields> so they can narrow the list directly instead of scrolling shapes.

opencli browser network --filter author,text,likes
# → only entries whose shape has ALL three fields as some path segment

• Matching: "any-segment" — field matches if it equals any segment of any shape path. Array indices [N] are stripped; $[\"nick name\"] unwraps. So $.data.items[0].author.name contains data, items, author, name.
• Combination: AND across fields.
• Case-sensitive (JSON keys are).
• Parse: ,-split, trim, drop empties, dedupe preserving first-seen order.
• Errors:
  • invalid_filter for \"\" / whitespace-only / ,,,
  • invalid_args when combined with --detail (mutually exclusive — one fetches a key, one narrows a list)
• Empty match is not an error — entries: [], count: 0, exit 0.
• Envelope adds filter: [...] (echo) and filter_dropped: N (dropped by --filter, separate from the existing static-resource filtered_out).
• Cache still stores the unfiltered capture, so later --detail <key> resolves requests that --filter hid.
• --raw / --all compose normally.

Test plan

• node node_modules/vitest/vitest.mjs run src/browser/shape-filter.test.ts src/cli.test.ts — 2 files / 68 tests pass
• New unit module src/browser/shape-filter.ts covers parse, segment extraction (dotted, array indices, bracket keys), AND matching, case sensitivity
• New integration tests in src/cli.test.ts cover: AND narrowing, container-segment match, 0-match empty result (not error), case sensitivity, --filter + --raw, --filter + --detail → invalid_args, invalid_filter for empty / commas-only, and that --detail still finds keys hidden by --filter (cache stays unfiltered)
• Skill docs updated (opencli-adapter-author/references/api-discovery.md, opencli-autofix/SKILL.md) with the new flag
• TypeScript `tsc --noEmit` clean