[PHP] Extract resumable fresh local index processing from PushPlan

[adamziel]

Moves fresh local index construction out of PushPlan so pull and push can use the same resumable filesystem scan.

FreshLocalIndexProcessor owns FileIndexProcessor, the fresh local index file, its saved byte offset, and the final sort. Its cursor contains every value needed by resume():

$processor = FreshLocalIndexProcessor::start(
    $fresh_local_index_file,
    $filesystem_root,
    $storage_path
);

do {
    $has_next_step = $processor->next_step();
    $processor->flush_pending_output();
    save_cursor($processor->get_cursor());
} while ($has_next_step);

$processor->close();

PushPlan now stores that cursor unchanged. It keeps the existing phase boundary between traversal and sorting, then starts FileSyncPatchPlanner exactly as before. The raw traversal, JSONL writing, output truncation, and sorting code are removed from PushPlan.

Testing

The focused tests cover sorted local-relative index entries, empty directories, resume after an uncommitted output tail, the separate sorting step, PushPlan behavior, bounded sender steps, and process-death resume.

[github-actions]

Pull pipeline performance — large-directory

Site: large-directory · 2,000+ plus targeted file-transfer scenarios files · 10,000 posts · 25,000 postmeta · PHP 8.5.9

Stage	PR	trunk	Δ	Status	Details
playground-sqlite-db-pull	10.12 s	9.71 s	⚪ +404 ms (+4.2%)	✓	condition=db-pull in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=lexer native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=selected trunk: condition=db-pull in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=lexer native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=selected
playground-sqlite-db-apply	3.85 s	3.81 s	⚪ +37 ms (+1.0%)	✓	condition=db-apply to SQLite in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=parser native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=verified native_ast=WP_MySQL_Native_Parser_Node sqlite_driver_parser=verified trunk: condition=db-apply to SQLite in PHP.wasm runtime=php.wasm 8.3 wp_mysql_parser=enabled mode=parser native_lexer=verified native_token_stream=WP_MySQL_Native_Token_Stream native_token_count=18 native_parser=verified native_ast=WP_MySQL_Native_Parser_Node sqlite_driver_parser=verified
Total	13.96 s	13.52 s	⚪ +441 ms (+3.3%)

_{Numbers carry runner noise; treat single-run deltas as directional, not authoritative.}

_{📈 Trunk performance history — commit-by-commit timeline.}

[adamziel]

Superseded by a single minimal PR based directly on trunk.