Add table context URL serializer

docs/tables_frontend_overhaul_implementation_plan.md

@@ -54,6 +54,7 @@ It is intentionally implementation-focused:
 | 2026-03-21 | P2.2 | Completed | Replaced the old `/diagnostics` and `/api` pages with lightweight compatibility routes that reuse a shared redirect component, preserve query strings and fragments, and replace browser history while forwarding into the canonical `Tools` routes. |
 | 2026-03-21 | P2.3 | Completed | Added a shared `RecentTablesState` service backed by browser storage, centralized the recents storage key, and started recording successful table visits from the `Tables` page so later omnibox and rail work has real shared data. |
 | 2026-03-21 | P2.4 | Completed | Added a shared `PinnedTablesState` service with browser persistence, centralized the pin storage key, initialized pin state in the `Tables` page, and added a first live pin/unpin action plus pinned status chips so later omnibox and navigation work have real saved pins to consume. |
+| 2026-03-21 | P2.5 | Completed | Added shared table-context URL types and a serializer, registered the serializer centrally, and started round-tripping table context through `/tables` and `/tools/diagnostics` so direct links restore the selected table and diagnostic cell context instead of relying only on local storage defaults. |
 
 ### Lessons Learned
 
@@ -77,6 +78,7 @@ It is intentionally implementation-focused:
 - Compatibility routes should stay declarative and shared. A single redirect component is enough for route forwarding and avoids copy-pasted `NavigationManager` lifecycle logic in page files.
 - Shared browser-backed state becomes more useful once one real page writes to it immediately. Recording recents from `Tables` now keeps later omnibox work from being blocked on synthetic placeholder data.
 - Shared pinned-state services also need one live writer early. A minimal pin/unpin affordance in the current `Tables` page is enough to validate persistence before the larger navigation surfaces consume pins.
+- URL serializers only pay off when wired into real pages. Using the shared serializer in both `Tables` and diagnostics now gives the project one verified round-trip path before the larger table-context service lands.
 
 ## Target Outcomes
 
@@ -368,7 +370,7 @@ Establish the shared shell, tokens, typography, and theme system that every dest
 | `P2.2` | Completed | Old `/diagnostics` and `/api` routes now forward into the canonical `Tools` routes with shared redirect behavior. |
 | `P2.3` | Completed | Recent critical-table visits now persist through a shared app-state service and are recorded from the `Tables` page. |
 | `P2.4` | Completed | Pinned tables now persist through a shared app-state service and can already be toggled from the `Tables` page. |
-| `P2.5` | Pending | Table-context URL parsing and serialization still needs a shared model. |
+| `P2.5` | Completed | Shared table-context URLs now parse and serialize through one helper and are consumed by `/tables` and `/tools/diagnostics`. |
 | `P2.6` | Pending | The shell omnibox is still a placeholder trigger. |
 | `P2.7` | Pending | Shared primitives for chips, tabs, drawers, and inspector sections are not extracted yet. |
 | `P2.8` | Pending | Table-selection logic still lives inside individual pages. |