feat: implement User Story 2 - Search and Discovery (P2)

Implemented 12 new MCP tools for search and knowledge graph navigation:

Search Tools (2):
- obsidian_search: Content search with folder filtering and case sensitivity
- obsidian_search_with_context: Search with surrounding context lines

Link Tools (5):
- obsidian_get_backlinks: Show incoming links to a note
- obsidian_get_outgoing_links: Show outgoing links from a note
- obsidian_list_unresolved_links: Find broken wikilinks
- obsidian_list_deadends: Find notes with no outgoing links
- obsidian_list_orphans: Find notes with no incoming links

Tag & Alias Tools (3):
- obsidian_list_tags: List all tags with optional counts
- obsidian_get_tag_info: Detailed tag usage information
- obsidian_list_aliases: List note aliases

Property Discovery Tools (2):
- obsidian_list_properties: List all vault properties
- obsidian_get_property_count: Get property usage counts

New files created:
- src/tools/search.ts (2 tools)
- src/tools/links.ts (5 tools)
- src/tools/tags-aliases.ts (3 tools)
- src/tools/properties.ts (2 tools)

Updated:
- src/tools/index.ts: Register all new tool modules
- src/validation/schemas.ts: Enhanced searchSchema with new parameters
- manifest.json: Added 12 new tools to tools array (21 total)
- tasks.md: Marked T046-T063 complete (18 tasks)

Build: ✅ 0 errors
Validation: ✅ Manifest passes
Total tools: 21 (9 US1 + 12 US2)
Tasks complete: 70/167 (41.9%)

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

src/validation/schemas.ts

@@ -144,8 +144,11 @@ export const moveRenameSchema = z.intersection(
 // Search parameters
 export const searchSchema = z.object({
   query: z.string().min(1, 'Search query cannot be empty'),
+  folder: optionalStringSchema,
+  limit: z.number().int().positive().max(1000).optional(),
+  caseSensitive: booleanFlagSchema.optional(),
+  contextLines: z.number().int().positive().max(10).optional(),
   ...formatSchema.shape,
-  ...paginationSchema.shape,
 });
 
 // Tag search parameters