docs(roadmap): resolve audit Open Question #2 -- renumber the colliding Phase 34/35 proposals

The audit's own Finding D-3 and Open Question #2: PHASE_ROADMAP.md's
Phase 33/34/35 headings describe different work than what the code
labels as Phase 33/34/35. Phase 33 was already resolved (see the prior
SUPERSEDED-note commit). This commit resolves the remaining two:

- 'Phase 34 -- Vector Search and Hybrid Retrieval' renumbered to
'Phase 76' -- the code already uses Phase 34 for the Forensic
Intelligence API (api/routes/forensics.py's own docstring,
tests/test_phase34_forensics.py), which is real, shipped, working
code.
- 'Phase 35 -- Plugin System and YAML Enrichers' renumbered to
'Phase 77' -- the code already uses Phase 35 for the entity-view
frontend tab wiring (tests/test_phase35_frontend.py), also real,
shipped, working code.

Chose to renumber the roadmap's still-unbuilt proposals rather than
rename the code's own docstrings/test file names, which would be far
more invasive. Moved to 76/77 (next unclaimed numbers after the
document's existing high point of 75) rather than inserting mid-
sequence, to avoid renumbering everything after them.

Verified: grepped the full document both before and after -- confirmed
neither 'Phase 34' nor 'Phase 35' is referenced as a dependency
anywhere else in the file before renumbering, and confirmed after the
edit that the only remaining mentions are inside this commit's own
explanatory notes.

PHASE_ROADMAP.md

@@ -311,8 +311,21 @@ Anti-forensics pattern: commit A -> commit B (change) -> commit C (reverts to A)
 
 ---
 
-### Phase 34 -- Vector Search and Hybrid Retrieval
-**Branch:** `feature/phase-34-vector-search`
+### Phase 76 -- Vector Search and Hybrid Retrieval
+
+> **Renumbered from "Phase 34" (August 2026, audit Open Question #2).**
+> The code already uses "Phase 34" for something else entirely --
+> `api/routes/forensics.py`'s own docstring says "Phase 34: Forensic
+> Intelligence API", and `tests/test_phase34_forensics.py` is a real,
+> shipped test file for that work. Renumbering this still-unbuilt
+> proposal to an unclaimed number was the smaller, less invasive fix
+> compared to renaming the code's own docstrings and test file names,
+> which are already referenced throughout this project's git history
+> and this repository's own audit trail. Confirmed via grep before
+> renumbering: nothing elsewhere in this document depends on or
+> references "Phase 34" by number.
+
+**Branch:** `feature/phase-76-vector-search`
 
 **Problem:** Keyword search misses semantically similar documents. Searching
 "Maharashtra road contract irregularity" does not find CAG reports about
@@ -336,8 +349,16 @@ Anti-forensics pattern: commit A -> commit B (change) -> commit C (reverts to A)
 
 ---
 
-### Phase 35 -- Plugin System and YAML Enrichers
-**Branch:** `feature/phase-35-plugins`
+### Phase 77 -- Plugin System and YAML Enrichers
+
+> **Renumbered from "Phase 35" (August 2026, audit Open Question #2).**
+> Same reason as Phase 76 above: the code already uses "Phase 35" for
+> the entity-view frontend tab wiring (`tests/test_phase35_frontend.py`,
+> built and shipped as part of this same audit-driven fix batch).
+> Confirmed via grep before renumbering: nothing elsewhere in this
+> document depends on or references "Phase 35" by number.
+
+**Branch:** `feature/phase-77-plugins`
 
 **Lazy-loading plugin architecture** -- new data sources added by dropping
 a YAML file in `enrichers/` with no code changes.