feat(routines): stored routine management (run/create/edit/drop) with plugin support

[debba]

What

Adds full management for stored procedures and functions, gated by a new routine_management driver capability (enabled for MySQL and PostgreSQL, opt-in for plugin drivers via manifest).

Run with parameters

• New Run… entry in the routine context menu opens a modal that loads the routine's parameters and collects values: per-parameter NULL checkbox and a "Raw" toggle (skips string quoting; defaults on for numeric types). OUT parameters are shown as informational.
• The driver builds a reviewable invocation script:
  • MySQL: OUT/INOUT go through session variables — SET @p = …; / CALL proc(@p); / SELECT @p AS p; — so outputs come back as a result set.
  • PostgreSQL: functions run as SELECT * FROM fn(...) (scalar and set-returning covered); procedures via CALL with NULL placeholders for OUT.
• Navigation-initiated auto-runs are now multi-statement aware (runAutoQuery in Editor.tsx): scripts get split and routed through execute_query_batch, which runs on a single pooled connection — required for the session-variable dance to survive.

Create / Edit / Drop

• New procedure/function ("+" on the Routines section): opens a dialect-aware starter template in an editor tab (DELIMITER-wrapped for MySQL, CREATE OR REPLACE … $$ … $$ for PostgreSQL).
• Edit: opens a re-runnable script — MySQL wraps SHOW CREATE in DROP IF EXISTS + DELIMITER; PostgreSQL reuses pg_get_functiondef (already CREATE OR REPLACE).
• Drop with confirmation modal. PostgreSQL resolves the exact identity signature via pg_get_function_identity_arguments and refuses to guess between overloads instead of dropping the wrong one.

Plugin integration

Four new DatabaseDriver methods (build_routine_call_sql, routine_create_template, get_routine_edit_script, drop_routine) ship dialect-neutral defaults, so existing drivers are untouched. For plugin drivers they are optional JSON-RPC methods: on "method not found" (-32601) the host falls back to the same generic SQL, so a plugin only implements what its dialect needs. Documented in the plugin-driver skill and added to plugins/manifest.schema.json (which is additionalProperties: false, so the capability had to land there too).

Also fixed in passing: routine context-menu actions on schema-scoped items (PostgreSQL sidebar) now carry the item's schema instead of always using the connection's active schema.

Testing

• End-to-end against a live MariaDB through the real driver code path: invocation script with IN+OUT params executed via execute_batch returns the CALL's result set and then the OUT value (SELECT @p_result → "got 7"); edit script, create template and drop verified working.
• cargo test: 782 passed — 16 new unit tests for the SQL builders (session-variable rendering, INOUT SET prelude, identifier/literal escaping, hostile parameter names, PG identity-signature drop).
• pnpm test: 2716 passed — 12 new tests for the parameter-assembly helper (routineCall.ts).
• tsc --noEmit and eslint clean. New i18n keys added to all 8 locales.

Relationship with #415

Independent branches off main, but they compose: with #415 merged, a CALL returning multiple result sets shows every set in its own tab. Until then, the Run flow works but only the first result set of a multi-result procedure is displayed (pre-existing #414 behaviour). Expect a trivial conflict on the mod declarations in drivers/mysql/mod.rs and on tests.rs when merging the second of the two.

Limitations

• SQLite has no stored routines; capability stays off and nothing changes there.
• PostgreSQL routines with multiple overloads: run/edit target the first match from information_schema (pre-existing behaviour of parameters/definition lookups); drop refuses explicitly.