Extract native incoming-Intent parser from AndroidDocumentsPlugin

[Renakoni]

Summary

Seventh PR of the semantic-decomposition series: moves ACTION_VIEW / ACTION_SEND parsing and classification out of AndroidDocumentsPlugin.java into a focused IncomingIntentParser that returns structured results. Behavior-preserving — event names, payload fields, error codes, messages, and log lines are unchanged.

Boundary

IncomingIntentParser.parse(Intent) returns one of six structured results: ignored, open-with document (URI), shared Markdown stream (URI), shared text (validated markdown + normalized MIME + raw title), or an open-with/share rejection carrying the stable code/message pair. The parser owns:

• action routing incl. the SEND_MULTIPLE rejection,
• the VIEW/SEND category allow-lists and content:// scheme checks,
• EXTRA_STREAM/EXTRA_TEXT extraction with their malformed-extra handling (incl. the Tiramisu parcelable API split),
• the shared-text MIME gate, byte-size validation via MarkdownCodec, and the EXTRA_TITLE→EXTRA_SUBJECT→fallback title resolution (returned raw; the plugin still normalizes to a .md name at emission, keeping naming with TODO 8's territory),
• the Markdown MIME/extension candidate rules (isMarkdownCandidate & co.) that the document read paths share,
• the parse-stage rejection logs, which move with the reasoning verbatim.

Per the TODO, the parser owns no UI or persistence. The plugin keeps the duplicate-intent guard (instance state), ContentResolver document reads, URI-permission persistence, all JSObject/event building and Capacitor listener notification — its incoming path is now a dispatch switch over the parser result, with the three emitters (emitOpenWithDocument, emitSharedStream, emitSharedText) carrying the previously duplicated read/emit bodies unchanged.

Testing

• New IncomingIntentParserTest (5 JUnit tests) locks the pure classification rules: Markdown extensions case-insensitively, exact Markdown MIME set, the plain-text-by-MIME vs extension-wins candidate rule, the any-text/*-or-empty shared-text gate, and MIME normalization. Native suite now 13/13 via gradlew testDebugUnitTest (CI-gated since Extract native Markdown codec from AndroidDocumentsPlugin #91).
• Intent-level behavior smoke-verified on the emulator with real intents via adb: SEND text/plain accepted end-to-end (event emitted, display name SmokeTitle.md resolved from EXTRA_SUBJECT), VIEW file:// rejected through the full parser with the preserved unsupported scheme: file log, and SEND_MULTIPLE rejected. (A shell-issued VIEW content:// is blocked by the OS before reaching any app — adb limitation; the open-with happy path is a verbatim move whose preceding checks the rejection smoke exercised.)
• compileDebugJavaWithJavac + assembleDebug green; Java-only diff, TS contract untouched.